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The loss of function of PhaC 1 is a survival mechanism that counteracts the stress caused by the overproduction of poly‐3‐hydroxyalkanoates in P seudomonas putida Δ fadBA
Author(s) -
Obeso José I.,
Maestro Beatriz,
Sanz Jesús M.,
Olivera Elías R.,
Luengo José M.
Publication year - 2015
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.12753
Subject(s) - biology , mutant , pseudomonas putida , biochemistry , function (biology) , carbon source , strain (injury) , klf4 , overproduction , gene , mutation , microbiology and biotechnology , anatomy , embryonic stem cell , induced pluripotent stem cell
Summary The poly‐3‐hydroxylkanoate ( PHA )‐overproducing mutant P seudomonas putida U Δ fadBA ( Pp Δ fadBA ) lacks the genes encoding the main β‐oxidation pathway ( FadBA ). This strain accumulates enormous amounts of bioplastics when cultured in chemically defined media containing PHA precursors (different n‐alkanoic or n‐aryl‐alkanoic acids) and an additional carbon source. In medium containing glucose or 4‐hydroxy‐phenylacetate, the mutant does not accumulate PHAs and grows just as the wild type ( P . putida U ). However, when the carbon source is octanoate, growth is severely impaired, suggesting that in Pp Δ fadBA , the metabolic imbalance resulting from a lower rate of β‐oxidation, together with the accumulation of bioplastics, causes severe physiological stress. Here, we show that Pp Δ fadBA efficiently counteracts this latter effect via a survival mechanism involving the introduction of spontaneous mutations that block PHA accumulation. Surprisingly, genetic analyses of the whole pha cluster revealed that these mutations occurred only in the gene encoding one of the polymerases ( phaC 1 ) and that the loss of PhaC 1 function was enough to prevent PHA synthesis. The influence of these mutations on the structure of PhaC 1 and the existence of a protein–protein ( PhaC 1– PhaC 2) interaction that explains the functionality of the polymerization system are discussed herein.